The invention relates to a surgical instrument with a tool which is located at the distal instrument end, with a stationary first grip part at the proximal instrument end, with an axially guided second grip part in the form of a reel, and with an actuation element for the tool, wherein the actuation element in connection with the second grip part is axially adjustable on adjustment of the second grip part.
A surgical instrument of the generic type is known from German Utility Model DE 84 15 222 U1. Here, a forceps at the distal end of the instrument is actuated by the surgeon carrying out a displacement movement between an axially fixed grip part and a reel. This displacement movement is transmitted via a wire led in a sleeve to the forceps, which then is correspondingly closed or opened.
A similar design has the surgical gripping element known from German published patent application DE 30 12 447 A1. Here also, a wire led in a sleeve transmits an axial displacement movement of a reel relative to the stationary grip to the tool. The wire is connected to the stationary grip and the reel to the actuation-side end of the sleeve, wherein the latter mentioned connection is created via a direction-reversal gearing.
With the known instruments, in particular with the application of smaller forceps, it is disadvantageous that, on account of the comparatively small displacement path of the reel relative to the stationary grip, a fine-touch actuation of the forceps jaw or a scissors arranged in place of the forceps is not possible. This is caused on account of the relatively short jaw part limbs and connecting rod, on which the pull wire engages with its distal end and whose proximal end is connected to the reel.
It is therefore the object of the present invention to develop further a surgical instrument of the generic type, such that the handling of the instrument is improved and a more fine-touch actuation of the instrument is possible. In particular with the application of smaller forceps, it should be possible to ensure a fine-touch actuation of the forceps jaw, which is still accurate.
The solution of this object by way of the invention is characterized in that by way of a lever system linked onto the second grip part and a stationary part of the instrument the adjustment path is geared down and the force exerted onto the reel is transmittable, geared up, to the actuation element.
The lever system may comprise two levers. With this in an advantageous manner, the one first lever with its one end is articulately arranged on the second grip part and with its other end is articulately arranged on the other second lever; the second lever with its one end is articulately arranged on the first lever and with its other end is articulately arranged on the stationary part of the instrument; and finally, the actuation element is articulately fastened between the two linkage points of the second lever.
Alternatively, the lever system may also comprise a single lever. With this the lever with its one end is articulately arranged on the stationary part of the instrument and with its other end is slidingly arranged in a guide of the second grip part; and the actuation element is articulately fastened between the two ends of the lever to this lever. The guide at the same time comprises a bore, which extends essentially perpendicular to the movement direction of the actuation element. It can in particular comprise a cylindrically formed section and a conically formed section connecting to this lever.
As an overload protection between the lever system and the actuation element, there may be arranged a spring element.